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Author Topic: Problems threading on the lathe  (Read 330060 times)

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Offline RICH

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Re: Problems threading on the lathe
« Reply #250 on: April 22, 2009, 06:11:41 AM »
ART,
Tried out the the MACH3GENERATION4 driver you posted back in reply #231. I used the SS & G76  for trying to cut multiple start threads. Single and double start were fine but no go here on the three start thread as the  timimg was off i believe. Lead start point on end of piece varied for the third thread start.
The threading  was short  (3/4" inch), but  overall all, by the time it's cutting the third start it would have been the equivilant of doing a single thread  of 2 1/4" long.

Would this be an applicable test for trying out the index timing?

Making an adapter so i can easily mount and try different slotted disc's for testing.
RICH

Offline ART

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Re: Problems threading on the lathe
« Reply #251 on: April 22, 2009, 07:46:59 AM »
Hi Guys:

  Actually, even if we only had a slotted wheel I could give you an indexable home. The question is if we can say withotu doubt that no slots are missed during the time the machine is on. If we KNOW that to be true, Itd be easy enough to give you a button that sets any particular slot to be the index slot. Youd simply revolve the spindle by hand to a certain spot, and hit a button that sets it as the index.  There are multiple ways to deal with such things but only if we know that the reading of the slots is absolute and we never lose any.

 Anyway, there are several things that can be done with an advanced Spindle control plugin that we can look at over time once we know if threading will work
under the proposed sheme. Id like to simply have multiple setup selection onthe plugin that allow for various configurations, each perhaps with known %error
tolerances on threads.

  More as data comes in I guess. :)

Thx
Art
Re: Problems threading on the lathe
« Reply #252 on: April 25, 2009, 10:21:50 AM »
So whats the best combination of hardware and software for lathe threading at this point ? I have both a single slot encoder disk and pickup as well as a qaud encoder with index pulse . I am running a cnc4pc breakout board and a smooth stepper , and not agaisnt rewiring etc to get the best posible setup for single point threading very basic single start threads

Offline ART

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Re: Problems threading on the lathe
« Reply #253 on: April 25, 2009, 11:06:33 AM »
Hi Guys:

  Heres a test driver.. Even if you use 1 pulse per rev Id like to know what happens when you try it. You have to load the driver, and the plugin enclosed.
You can set the INDEX timeing as normal, and if you dont have a slotted wheel, set the TIMING input ot the same as the INDEX input. This will simulate
a slotted wheel with 1 slot. Id be interested in your results as a diagnostic. PP mode only though.

 You can see the results with the plugin/Advanced Spindle menu item, you shoudl see a stable RPM on the second DRO, but Id like to knwo what they all say.
Take note it takes 64 revs with single slot to get a proper RPM  because its assuming a 90 slot wheel at the moment, and averaging over 64 slots.

Thx
Art

Offline Chip

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Re: Problems threading on the lathe
« Reply #254 on: April 25, 2009, 04:05:05 PM »
Hi, Art

Hear are some pic's to look at with simulated pulses single and simulated 4 slot doing G76 threading, Very Nice.

Seems to lock in the Pulse Frequency on my problem computer fine also.

Thanks, Chip

Offline Chip

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Re: Problems threading on the lathe
« Reply #255 on: April 25, 2009, 04:25:44 PM »
Hi, Art

Hears 4 more, 2 with 25 and 2 with 251 slots simulated.

Now if you'd make the "Corr" Barber Pole bidirectional, I'd have a Sync-Row-Scope to Adjust the ratio.

Chip
« Last Edit: April 25, 2009, 05:33:13 PM by Chip »

Offline ART

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Re: Problems threading on the lathe
« Reply #256 on: April 25, 2009, 05:57:11 PM »
Chip:

 Excellent! , thanks. Your numbers are good. Is the Slot based RPM steady? Mine stays within 0.xx of 1 RPM typically.
Correction is not yet turned on, so slowing the spindle will only show you a Q value which indicated exactly how much correction
will be applied in realtime as the thread progresses. Gree means its slowing down from start, red means its speeding up.

 Yours seems perfect as long as the slot based RPM is steady.

Thx
Art

Offline Chip

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Re: Problems threading on the lathe
« Reply #257 on: April 25, 2009, 06:47:11 PM »
Hi, Art

I'll try it on my good computer in awhile, Using 2 non locked time sources, Need to find a divide/multiply chip and source off one timebase hear to test further.

Slot based RPM steady? Mine stays about the same as you's, 0.xx of 1 RPM. Flashes red/green when threading, Then red or green with rapids.

Chip

Offline RICH

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Re: Problems threading on the lathe
« Reply #258 on: April 25, 2009, 11:12:56 PM »
Hi ART,
Screen shots using MACH version 3.042.027 along with Chips Lset.
Single index slot.
RICH

Offline RICH

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Re: Problems threading on the lathe
« Reply #259 on: April 25, 2009, 11:17:09 PM »
ART ,
Here are some more as i changed the rpm twice as shown in
1&2A and 3&4A screen shots.
BTW, you can thanks Chip helping me get the driver test set up on my PC.
RICH